At the beginning of the relaxation process (\(t=0\) ) for a given strain, the stress is the same as reflected in the loading curve in Fig. REF . For short time, the stress remains almost constant for all the strain values and then starts to decrease. We also observe in Fig. 5 that the long time tail part of these curves shows a power-law decay (linear behavior in the log-log scale). Therefore, unlike a liquid where the stress becomes zero on the structural-relaxation time scale, the build-up stress in the deformed glass never relaxes to zero. In other words, the sheared configuration can never relax to equilibrium completely. As a result, we always find a persistent residual stress within the experimental time window. These results obtained from our simulation are very generic and observed in many soft materials like colloids, molecular glass, etc via experiments [1]}, [2]}, [3]}, [4]}, [5]} and simulations [6]}, [7]}. The mode-coupling theory of glass transition also predicts the shear residual stress in glass dependent on shear history [8]}, [9]}. The upshot of this section is that the memory inherited by the sample from the preparation protocol persists forever and affects the mechanical properties and relaxation dynamics in the sheared configuration. Therefore, the glassy sample in the plastic flow regime can not be completely characterized by the associated thermodynamics variables only.
